A 62-year-old white postmenopausal woman is concerned that she may have osteoporosis. Her older sister was diagnosed with osteoporosis at age 60 years and has had several vertebral compression fractures. The patient has avoided dairy products most of her life. She smoked a pack of cigarettes daily for 40 years but does not drink alcoholic beverages. She takes no medications or nutritional supplements. She has never received calcium supplementation or hormone replacement therapy. She had no other medical problems and her physical examination is normal. She is 170 cm (67 in) tall and weighs 69 kg (152 Ib).
Which of the following tests would show whether this patient has osteoporosis?
A. Measurement of markers of bone resorption
B. Bone biopsy of the iliac crest
C. Dual-energy X-ray absorptiometry of the spine and hip
D. Ultrasound of the heel
E. Radiographs of the spine

The correct answer is C
Educational Objectives
Identify the correct test to diagnose osteoporosis in a postmenopausal woman.
This woman has several risks factors for osteoporosis: she is a postmenopausal white woman and has not received hormone replacement therapy. She smokes, consumes an inadequate amount of dietary calcium, and has a significant family history of osteoporosis. Given this patients risk factors, it is necessary to determine if she has osteoporosis. The diagnosis of osteoporosis is made by dual-energy X-ray absorptiometry. This technique is considered the gold standard because it has been extensively validated against fracture outcomes, requires relatively short scanning times and can measure bone loss in all areas of the skeleton with a high degree of accuracy and reproducibility.
No other laboratory tests or other radiographic examinations can reliably identify individuals with osteoporosis. Measurement of markers of bone resorption such as urinary hydroxyproline or serum collagen cross-links may be useful in assessing future fracture risk or in identifying persons at risk for rapid bone loss, but these markers cannot be used to diagnose osteoporosis. Bone biopsy should be reserved for the work-up of rare or puzzling causes of osteoporosis. Measurement of bone mass with quantitative ultrasound should be used for risk assessment. The results from this test cannot be used with the World Health Organization criteria for the diagnosis of osteoporosis. Standard radiographs are not sensitive indicators of bone loss since they do not consistently demonstrate significant demineralization until 30% to 40% of the bone mineral has been lost.